Abstract: An oil-free electron source including a vacuum chamber within which a vacuum is maintained. A rigid insulated receptacle and an anode extend into the vacuum chamber and are mounted to opposite ends of the housing. A cathode-focus electrode assembly is mounted to an outer end of the receptacle and is suspended within the vacuum chamber by the receptacle. A high voltage connector is inserted into the receptacle and conveys voltage in an oil-free environment. The cathode and anode surfaces face each other and are aligned with respect to each other along an electron beam axis. The electron source may be provided within an electron beam scanner including a patient table, an x-ray source and detector obtaining x-ray scans of a patient, and a focus member directing an electron beam onto the x-ray source.

Abstract: A radiographic image forming apparatus having a radiation source for irradiating conical radiation to a test body; a stimulable phosphor plate, arranged opposite to the radiation source with the test body sandwiched in-between for recording an intensity of radiation having passed through the test body; a rotation/displacement section for relatively rotating and displacing the radiation source with respect to the test body, by placing the test body at a rotation center; a radiation controller for controlling a radiation from the radiation source; a recording section for recording at least one sinogram into the stimulable phosphor plate by the radiation; a reading section for reading a sinogram recorded by the recording section; and an image processing section for forming a two-dimensional or three-dimensional tomographic image by reconstructing a sinogram read by the reading section.

Abstract: An x-ray tube has a stationary vacuum housing, in which are arranged an electron-emitting cathode and a ring anode with an impact surface on which the electron beam, accelerated by an electrical field, is incident, as well as a deflection system to focus and deflect the electron beam. The ray exit window of the x-ray tube is round, lies in the plane perpendicular to the central axis of the x-ray tube, and terminates one side at the vacuum housing. The impact surface of the ring anode is beveled and is aligned to the ray exit window. A diaphragm is provided in front of the ray exit window that defines a circular opening for the x-ray radiation. The ring anode is surrounded by an annular anode cooling arrangement.

Abstract: The present invention provides methods and devices which improve a time resolution of a scanner by segmenting the data and generating a plurality of low resolution images. The low resolution images may then be combined to reconstruct a full image of a slice of a target. Such a method improves the time resolution of the scanner while maintaining the radiation dosage and time of the scan.

Abstract: A stationary CT system comprising at least one annular x ray source assembly comprising a plurality of respective x ray sources spaced along the annular x ray source assembly. Each of the x ray sources comprises a respective stationary x ray target, an electron beam focusing chamber; an x ray channel; an electron beam source disposed in a spaced apart relationship with respect to the respective stationary x ray target; a vacuum chamber disposed in between the electron beam focusing chamber and an insulating chamber where the insulating chamber houses the electron beam source; a radiation window at a pre-defined angular displacement from the respective stationary x ray target and the x ray channel; and a target substrate attached to the respective stationary x ray target.

Abstract: A multisource type X-ray CT apparatus including a fixed sensor array, a fixed vacuum chamber, and an X-ray generation unit. The X-ray generation unit includes a cathode and an anode which are fixed in the vacuum chamber so as to surround the sensor array, a gate array including a plurality of grid electrodes which are densely fixed between the cathode and anode and which include holes for passing the electron beams, a power source which applies a bias voltage to the grid electrodes of the gate array, and a controller which controls the power supply operation from the power source so as to select the grid electrode suitable for image pickup from the gate array in accordance with an image pickup portion of the subject and to release the bias voltage applied to the selected grid electrode.

Abstract: A method and apparatus is disclosed for mapping the relevant material properties of a log, such as knot location and extent. The outer shape of the log under bark is also revealed using this method, and the boundary between the heartwood and sapwood is accurately mapped. The apparatus includes three x-ray sources and arrays of x-ray detectors, for measuring the attenuation of the wood in the log. Deviations in attenuation are related to changes in density, which are indicative of knots and other defects. Accurate estimates of shape, density and knot location render improved sawing decisions at the headrig of a sawmill, which improve the yield of high quality lumber from a given log. The techniques may also be used in a system for sorting logs according to quality.

Abstract: A scanning electron beam computed tomographic system is provided with a sub-collimation system that passes X-rays emitted by a beam spot formed by an electron beam that is scanned across an X-ray emitting target, which X-rays would not otherwise reach an object under X-ray examination with the system. The sub-collimation system includes phantom-like objects that cause X-rays to be blocked, or passed, through to X-ray detectors depending primarily upon the beam spot position and, secondarily, on the beam-spot shape. Detector output signals may be used in real-time to control at least one characteristic of the electron beam-spot in a closed-loop correction system.

Abstract: A method and apparatus are disclosed for reducing variation in a spot size of an electron beam at a target due to multipole aberrations in an electron beam tomography (EBT) scanner. A magnitude of a DC voltage applied to a positive ion electrode (PIE) within the EBT scanner is adjusted and an orientation of a non-circular aperture of the PIE is aligned with respect to the electron beam. A profile of the spot size is monitored while adjusting the magnitude of the DC voltage and while aligning the orientation of the non-circular aperture of the PIE until the variation in the spot size is sufficiently reduced.

Abstract: A digital tomography system includes an electron source that provides a beam of electrons, and an electromagnet assembly that receives said beam of electrons and is configured and arranged to direct the beam of electrons along a selected path, wherein the assembly provides a redirected beam of electrons. The system also includes a target that is struck by the redirected beam of electrons and generates a cone of x-rays, and a slit collimator that receives the cone of x-rays and generates a fan beam. A first line of detectors is positioned to detect x-rays that pass through the object under inspection, and provide sensed signals indicative thereof to a controller that receives the sensed signals and forms a displayable image of a selected plane through the object under inspection.

Abstract: The origin of a cone or fan beam of B, &ggr;, or x radiation is moved in a continuous path such as a circle or is stepped among a two-dimensional grid of preselected points. The cone beam of radiation passes through a patient (14) in an imaging region (12) and is detected by a detector array (16). A data collection circuit (20) samples the detector array to generate radiation intensity sub-images. A circuit (56) monitors the shifting of the focal spot and controls an image shifting circuit (58) to shift physical coordinates of the sampled sub-image analogously. A sub-imaging combining circuit (60) interleaves or otherwise combines spatially shifted sub-images. In one embodiment, the combined sub-images forms a higher resolution composite image representation. In another embodiment, a plurality of combined, spatially shifted sub-images are collected at angularly offset orientations around the subject and are reconstructed into a higher resolution composite image representation.

Abstract: An X-ray computer tomography scanning system for imaging the internal structure of a human being including a source that projects a substantially conically shaped X-ray beam along a path on to a subject such that at least a portion of said beam is transmitted through said subject and a detector array that detects the portion of the beam transmitted through the subject and operative to generate electronic signals in response to the beam transmitted through the subject that projects on to said detector array. The system also including a patient support structure for supporting the subject and rotating said subject about an axis intersecting with and substantially perpendicular to the path of the beam, wherein said subject is constrained such that the subject remains in the path of said beam and an airbag restraining mechanism attached to the support structure for holding the subject in its position.

Abstract: A system and method for non-destructive examination of parts using three-dimensional CT imagery. The system comprises a computer controlled x-ray source, a scintillator screen, and an amorphous silicon sensor array, which electronically records and transmits a series of images taken from different angles back to the computer system having a CAD/CAM software program. The part being examined is stored as a CAD/CAM record. The various images from the silicon sensor array are stored in the computer system and reconstructed as a three-dimensional CT image. That CT image is converted to the CAD/CAM coordinate space so a comparison between the CT image and the stored drawing of the part being examined may be made to detect any defects in the part. The overlaid or superimposed images are displayed for an analyst so that determination of a defect and a location can be made.

Abstract: A system and method for performing computed tomography without having to use a complicated mechanical device to move an x-ray source about an object being scanned. Instead, this invention uses flexible waveguides such as optical fibers to direct the x-ray beams generated from the x-ray source. The waveguides direct the x-ray beam to the object at predetermined orientations and distances. A multiplexing unit optically coupled to the x-ray source and the waveguide, steers the x-ray energy from the x-ray energy source to the waveguide.

Abstract: A method of producing complex motion or spiral tomography images in tomographic imaging, comprising the steps of positioning an object to be imaged in a fixed position, arranging a radiation source on one side of the object to be imaged, arranging a detector on a second diametrically opposed side of the object to be imaged from the radiation source, the detector receiving radiation from the radiation source, while the radiation is being received, rotating the radiation source and the detector substantially around a vertical axis passing through the object to be imaged in a controlled manner whereby a tomographic effect is produced, while the radiation is being received, moving the radiation source in a first vertical direction, while the radiation is being received and simultaneously with the step of moving the radiation source, moving the detector in a second vertical direction opposite from the first vertical direction, and wherein the radiation source and the detector are moved independently from one anoth

Abstract: An X-ray tube assembly includes a hermetically-sealed annular frame, spaced apart cathode and anode rings and an electron excitation device. The frame surrounds an exterior central passage for receiving a patient therethrough and has an interior chamber with a vacuum and an X-ray transparent window ring surrounding the central passage. The cathode and anode rings are stationarily mounted to the frame and disposed within the interior chamber. The cathode ring has circumferentially arranged side-by-side filaments each separately excitable by the electron excitation device to cause flow of electrons in an e-beam to a target portion of the anode ring such that an X-ray beam is produced that exits the interior chamber passing through the transparent window ring and that can be moved around the patient disposed within the central passage.

Abstract: An X-ray computed tomography apparatus having a two-dimensional detector allows X-ray shadowgraphs to be alternatively produced with using one or several detector rows. For this purpose, a slot diaphragm near the tube and a slot diaphragm near the detector are provided. For the superposition of the shadowgraphs of the individual detector rows, an on-line computing method is used that includes a deblurring filter for the reduction of image blurring due to table motion, and a method for scatter radiation correction in a multirow or matrix detector.

Abstract: Tuning, integrating, and operating an electron beam CT scanning system is simplified by using the fringe field from dipole magnets arranged as a chicane to focus the electron beam, thus replacing conventional quadrupole and solenoid coils. Preferably four "chicane" dipole magnets are series-coupled with the windings in the downstream deflection magnet, such that the chicane magnet X and Y coils are energized 90.degree. out of phase with the deflection magnet coils. The alternating current polarity in the chicane magnets creates an "S"-shaped electron beam trajectory that adequately uniformly focuses over the full cross-section of the electron beam. Winding the coils with a cosine distribution permits rotating the magnetic fields to change the azimuthal and deflecting planes of the electron beam, without disturbing the deflection angle and focusing properties.

Abstract: A rotating-patient computed tomography scanning system in which the detector offset is measured in real time for each scan. At least one x-ray--absorbent reference structure is disposed in the field of view, so that a projection of the reference structure is present in every view of the patient. The position of the reference structure can be expressed in terms of the detector offset for each view of the patient. The detector offset for a given image can therefore be determined at the time the image data is obtained. The offset value is used in the data obtained from the current scan to reconstruct images that are free of artifacts that are caused by errors in the detector offset.

Abstract: Computed tomographic ("CT") x-ray scanning yields a discrete set of measurement values that are line integrals of attenuation coefficients .mu.(r), which attenuation coefficients may be obtained using suitable reconstruction techniques. Electronic beam computed tomograph ("EBCT") systems add error to the reconstructed attenuation coefficients owing to their unique cone geometry. A method is provided that reduces such errors. At least two scans, "tilted" by the system cone angle, collect data in the neighborhood of a reference plane normal to the system z-axis. These scans are rebinned into parallel projections, and a series expansion is considered for variation of .mu.(r) in the vicinity of the reference plane. If a first order series is considered sufficient, then two scans are required to estimate the slope A of the variation in data. The data can then be corrected for the "tilt" and line integrals on the reference plane normal to the z-axis obtained.

Abstract: A nondestructive test apparatus for testing a work is formed of a fixed radiation generating device; a rotatable work holding device situated near the radiation generating device; and a rotatable radiation image taking device situated near the work holding device at a side opposite to the radiation generating device. The radiation image taking device rotates or swings in accordance with rotation or swinging of the work holding device at a same angle thereto. The radiation image taking device receives and accumulates images of the work held on the work holding device and radiated by the radiation generating device while the work is being rotated or swung. It is possible to quickly obtain a sectional image with the relatively simple and compact structure. The test or inspection efficiency can be improved.

Abstract: An x-ray computed tomography apparatus with electronic scanning of a ring-shaped anode has a solenoid coil for space-charge compensation which allows access to the anode. The solenoid coil is constructed of multiple parts so that a connector part can be released from a base part and the anode is thereby made accessible.

Abstract: An x-ray generator has a beam guidance system including an air coil and a toroidal solenoid coil, a ring anode surrounding the patient to be examined and arranged axially offset relative to the beam guidance, and individually driveable electron-optical components couple the electrons, which orbit on a circular specified path in the magnetic dipole field of the air coil, out of that path, deflect them in the axial direction, and focus them onto a segment of the ring anode allocated to the respectively activated out-coupling element.

Abstract: An arrangement for producing an x-ray beam in a computed tomography apparatus allows a scanning of the annular anode by the electron beam to ensue without any gap around the entire circumference of the anode. The electron beam is deflected by kick magnets from an injection circle onto a working circle and, proceeding from the working circle, onto the annular anode for causing an x-ray beam to be emitted from the anode as the point of incidence of the electron beam on the anode moves around the anode circumference.

Abstract: An anode for an x-ray tube has an incident surface on which an electron beam is incident for generating x-rays emanating from a focal spot. In at least that region wherein the focal spot is located during operation of the x-ray tube, the incident surface has a step-like structure with end faces that reside at a substantially right angle relative to the electron beam during operation of the x-ray tube. The end faces are connected by respective sidewalls, and backscattered electrons from the end faces strike the sidewalls and generate x-rays in addition to x-rays emanating from the end faces struck by the electron beam, thereby improving the efficiency of x-ray generation. A similar improvement can be achieved by an anode having a roughened surface in the region of the focal spot.

Abstract: In a scanning electron beam CT system, spherical aberration of the electron self-forces produces a deleterious halo around the final electron beam spot, causing loss of definition in the image rendered by the system. The spherical aberration is caused by non-uniform electron beam current density, and by non-uniform distribution of positive ions in the transition region of the beam-optical systems. The non-uniform electron beam current density depends upon the axial position of the electron gun cathode, while the transition region ion distribution depends upon the potential coupled to the washer-shaped positive ion electrode ("PIE") used to segregate the upstream and downstream portions of the electron beam. In the present invention, the beam spot halo is minimized (if not eliminated), and image definition is maximized by selecting the electron gun cathode axial position and the PIE potential such that their contributions to spherical aberrations at the final beam spot cancel.

Abstract: In an apparatus and a method for generating an x-ray beam circulating through a polar angle .phi. of 2.pi. that enables fast computed-tomographic scans is to be generated, an electron beam is generated with a predetermined energy and is injected into a beam guide that guides the electron beam on a spiral path in a plane by means of an axial magnetic field. At a location selectable in the .phi.-direction, the electron beam is deflected perpendicularly to the plane and onto an essentially annular anode arrangement, so that, proceeding from the point of incidence of the electron beam, x-rays directed onto the center of the anode arrangement are generated. For a scan, the selectable location at which the electron beam is deflected out of the plane is advanced along the spiral path, so that the point of incidence of the electron beam onto the anode arrangement advances correspondingly.

Abstract: An x-ray computed tomography apparatus is operated so that a reconstruction of arbitrarily selectable volume regions can be accomplished. A Fourier reconstruction is implemented based on parallel data in planes that are inclined by the angle .phi. relative to a plane perpendicular to the z axis.

Abstract: In an x-ray beam computed tomography apparatus having a ring anode scanned by an electron beam for producing an x-ray beam which rotates around an examination region, measurement of the intensity distribution in the electron beam is enabled at various locations of the ring anode during operation. For this purpose, the ring anode can have at a number of locations around its circumferential direction, insulated sub-anodes with an insulating interspace therebetween, to which a measuring arrangement for measuring the charge distribution, and thus the intensity distribution, in the electron beam is connected. The charge distribution is measured when the electron beam sweeps the interspace between two sub-anodes.

Abstract: In an electronic x-ray computed tomography apparatus that enables a scanning of approximately 360.degree., the electron beam is guided in an annularly fashioned magnet arrangement that has a U-shaped cross section. The U enables the guidance of the electron beam to the annular anode and enables the emergence of the x-radiation. The magnet arrangement is composed of a number of side-by-side U-shaped magnet elements arranged to form an annulus with a coil for excitation of the magnet element respectively arranged on the cross bar of each U. A single magnetic arrangement is thus used to generate both the electron beam guidance field and, by means of a sudden polarity reversal of a magnet element disposed at a desired deflection location, the deflection field.

Abstract: A scanning electron beam CT system generates an electron beam along a beam source axis offset from the scanner axis, or axis of symmetry, thereby permitting the X-ray subject to pass completely through the stationary gantry. The electron beam is produced with the first drift tube region of an evacuated housing chamber, and is directed downstream toward a second region that includes a gantry. A scan target and a tuning target, each concentric with and defining a plane normal to the system axis of symmetry, are located in the gantry. A beam optics system, through which the electron beam passes, is located within the housing intermediate the electron gun and gantry. A control system focusses and scans the electron beam upon the scan target, maintaining a beam spot of desired quality. Upon impingement by the scanning beam spot, the scan target emits a fan beam of X-rays.

Abstract: This invention provides a compact X-ray CT system capable of obtaining an X-ray CT image having high resolution at a high speed by deflecting a predetermined electron beam and causing the finely focused electron beam to scan on an arcuate anode target inside the same plane as the arcuate anode target for an X-ray source. The anode target for an X-ray source and a detector are disposed in the form of arcs inside substantially the same plane so as to face each other. The electron beam emitted from an electron gun is guided to a deflector through a lens system, is then deflected to a arc form trajectory by a uniform magnetic field generated by the deflector and is guided to the anode target after a reverse magnetic field is applied to the electron beam at a desired position. This electron beam is caused to scan on the anode target at a high speed so as to move the generation position of the X-ray and thus to obtain a sectional image.

Abstract: X-ray images are produced on a monitor display screen by situating the subject between a detector having a minute x-ray sensitive area and an x-ray source having an extensive anode plate on which an x-ray origin point is swept in a raster pattern similar to the raster of the display monitor. Operating parameters of the x-ray source are controlled by digital data processing circuits which enable magnification of operator selected areas of the image by reducing the size of x-ray source raster pattern and repositioning of the raster pattern on the anode plate in response to operator actuation of one or more computer input devices. In the preferred form, the system also enables image enhancements and control of image characteristics such as contrast and brightness in response to actuations of the input devices or in response to programming. X-ray exposure and image acquisition time may be reduced by operator selection of only specific areas of particular interest for high resolution scanning.

Abstract: A beam position detecting device wherein the intensity of a radiation beam from a synchrotron ring is measured on the basis of electric currents flowing through two wires, while accumulated electric current in the synchrotron ring is measured by using a current transformer. The beam position can be determined accurately on the basis of these measured values.

Abstract: An x-ray collimator is described which is useful in an electron beam (EB) computed tomography (CT) scanner of the type in which a rotating electron beam is directed to impinge upon a ring-shaped target and the x-rays generated in response thereto are directed to a ring shaped detector array spaced therefrom. The collimator consists of an x-ray blocking septum having an aperture therein, the septum being located in a fixed position substantially co-planer with the planes of the target and the detector, so as to block all x-rays directed from said target to said detector except those which pass through said aperture. Tomographic slice width is determined by the "view" from the spot where the electron beam impinges upon the target, through the aperture, to the detector, and is variable by adjusting the position where the electron beam impinges upon the width of the x-ray target, and in a preferred embodiment, the position of a movable ring.

Abstract: A method of image processing is provided for generating an image of an object in a computer X-ray tomography apparatus having an X-ray source and a detector. The method desirably permits relatively coarse spacing between adjacent detector views and correspondingly lowers exposure to X-ray radiation while maintaining a high resolution image. The method includes the step of acquiring actual detector data for multiple views of the object. After actual detector data is acquired for adjacent views of the object, the actual detector data from these adjacent views is interpolated to obtain virtual detector data between the adjacent views as though a virtual detector had been placed therebetween. The actual detector data and the resultant virtual detector data is then mapped into Radon space. The process is repeated until Radon space is sufficiently filled with actual detector data and virtual detector data to permit image reconstruction.

Abstract: In a helical dyamic scanning X-ray CT imaging system, an X-ray source is continuously moved on the same orbit during plural helical scanning operations by controlling a projection direction and a translation of a biological body that is to be examined medically. The helical dynamic scanning X-ray CT imaging system includes a system for helically scanning the biological body as the body is translated along a Z-axis to obtain projection image data of the body along the helically scanned path. Radiation is projected from a radiation source to the biological body being translated along the Z-direction as the radiation source simultaneously moves around the translated biological body. The helical scanning process is carried out during at least first and second helical scanning operations while detecting a radiation angle of the radiation source being detected.

Abstract: A microtomographic system (10) for generating high-resolution, three dimensional images of a specimen (16) is disclosed. The microtomograph system includes an x-ray generator (12) that produces an x-ray beam (14), a specimen holder (18) that holds the specimen in the beam, and an x-ray detector (20) that measures the attenuation of the beam through the specimen. Two projections of each view of the specimen are made with this microtomographic system. Each projection is made with a different intensity x-ray beam. After the projections of one view of the specimen are made, the specimen is rotated on the specimen holder and another set of projections are made. The projections of each view of the specimen are analyzed together to provide a quantitative indication of the phase fraction of the material comprising the specimen. The projections of the different views are combined to provide a three-dimensional image of the specimen.

Abstract: In a scanning electron beam CT system, the electron beam is focused by controlling the distribution of beam-generated ions electrostatically. The upstream (self-expanding, de-focusing) beam region and downstream (converging, self-focusing) beam region are distinguished by the absence or presence of beam-generated positive ions. The relative lengths of these two beam regions are electrostatically controlled such that beam de-focusing in the upstream region compensates for beam self-focusing in the downstream region. In this fashion, essentially zero external focusing strength is required, and the magnetic focus coil used in the prior art is eliminated. Located downstream from the electron gun, a positive ion electrode ("PIE") determines the position of the boundary between the two regions, and thus the relative length of each region. The PIE is a disk-like electrode, mounted coaxially to the beam optic axis within the drift tube, and coupled to a large positive potential.

Abstract: A computer tomography apparatus has an anode in the form of a partial ring along which a focus is electronically moved to generate a scan beam from different directions, and a partial ring detector which generates a number of data sets from the attenuated radiation at the different directions, includes a computer wherein the data sets are weighted independently of the measured values so that image reconstruction can be undertaken with a standard computer tomography method, such as convolution and back-projection. The weighting is selected so that the boundaries of regions having constant values represent smooth curves in the sinogram. The image can thereby be reconstructed without complementary interpolation, which is normally required in computer tomography systems having a partial ring x-ray source and detector.

Abstract: A method and apparatus for processing three-dimensional video signals representing a solid subject comprises, radiating the subject, receiving radiation from the subject with receptors on three axes intersecting the subject to produce three planar images of the subject volume normal to the three respective radiation axes. The picture elements of the three planar images are converted into three corresponding sets of planar video pixel signals which are converted into voxels and written at the three radiation axes into superimposition in a three dimensional storage matrix such that coincidence of three pixels in the three respective images stores a single voxel representative of the superposition of the three pixels. The voxels in the matrix can then be addressed by a view selector at an angle other than the three original radiation axes to read the selected two dimensional view out of the matrix to a display or recorder.

Abstract: A parallel processing architecture and method, based on the 3D Algebra Reconstruction Technique (ART), for iteratively reconstructing from cone beam projection data a 3D voxel data set V representing an image of an object. The cone beam projection data is acquired by employing a cone beam x-ray source and a two-dimensional array detector to scan the object along a source scanning trajectory to obtain, at each of a plurality of discrete source positions .theta..sub.i on the source scanning trajectory, a 2D measured cone beam pixel data set P.sub.i. The 3D voxel data set V is subdivided into or organized as a plurality m of independent voxel subcubes V.sup.0 through V.sup.m-1 each containing a plurality of voxels. As a result of the subdivision of the 3D voxel data set V into voxel subcubes, the 2D measured cone beam pixel data set P.sub.i (measured projection data array) is correspondingly subdivided for each source position .theta..sub.

Abstract: A scanning electron beam computed tomography scanner is disclosed herein and includes means defining a vacuum chamber, means for producing an electron beam at one location in the chamber and for directing it to a second location therein, a target located at a third position therein of the type which produces X-rays as a result of the impingement thereon by the electron beam, means for focusing the beam onto the target in the form of a beam spot and for scanning the beam spot across the target along a particular scan path in order to produce X-rays, and means for monitoring the profile, position, and orientation of the beam spot at a plurality of locations along the scan path. The specific scanner disclosed also includes an arrangement for determining from the signals produced by the monitoring devices if the beam spot conforms to as desired profile, position, and orientation and automatically adjusting the electron beam such that its profile, position, and orientation conform to desired values.

Abstract: In a radiographic apparatus, a source of radiation is arranged to scan a planar spread of radiation in a plane about the body of a patient being examined. A plurality of detector devices is arranged to provide data representing the absorption of the radiation along a plurality of paths within the spread, for different orientations in the plane, for processing to determine a distribution of absorption coefficients for a planar slice of the body. The arrangement is such that a predetermined number of the detector devices are irradiated by the spread of radiation at any time and the actual devices irradiated change progressively as the scan progresses.

Abstract: An electron beam x-ray computer tomography scanner is improved so that a compact, tiltable configuration without mechanical motion is achieved. By introducing the electron beam in a direction which is largely parallel rather than perpendicular to the scan plane, the long large diameter evacuated electron beam pipe of prior art is eliminated. As a result, the scan system according to the invention enjoys compact dimensions compared to those of prior art, and free access to the scan region from both the front and back of the scanner is possible.

Abstract: An X-ray computer tomography system with a stationary ring anode and a plurality of stationary electron sources for the construction of fast scan images from the inside of an object is improved in such a way that there is free access from both sides of the scan region, that the gantry unit can be tilted, and that the image quality which can be achieved is comparable to that of conventional tomography systems with mechanical motion of the anode. A plurality of electron sources are configured in proximity to the ring anode on a stationary ring, with each source being capable of sweeping its respective electron beam over a portion of the anode ring.

Abstract: An X-ray computer tomography system with a ring anode and substantially without mechanically moving parts for the production of fast image slices from the inside of an object is improved in such a way that a detector ring is comprised of two adjacent parallel partial detector rings of substantially equal size, whereby the detector ring is arranged within and coplanar to the anode ring. The two partial rings of the detector ring are displaced in a direction largely pependicular to the scan slice so that a ring-shaped detector ring gap is formed between them through which the fan beam coming from the focal spot on the anode passes.

Abstract: An X-ray tube for a CT apparatus comprises a ring-shaped vacuum tube containing a fixed cathode having a thermion emitting surface, a ring-shaped fixed anode, and a ring-shaped rotatable cathode interposed between the fixed cathode and fixed anode. The rotatable cathode defines a thermion receiving surface opposed to the thermion emitting surface, and a thermion emitting portion opposed to the fixed anode. Thermions are emitted from the thermion emitting portion toward the fixed anode while the rotatable cathode is suspended to non-contact state and rotated at high speed. With the thermions being accelerated and colliding on the fixed anode, an X-ray is generated toward the center of the vacuum tube. The X-ray generating position moves at high speed along a circumferential surface of the fixed anode with rotation of the rotatable cathode.

Abstract: A high-speed scan type X-ray generating apparatus for scanning X-ray generating positions along a circumference of an examinee, in which an electron beam is emitted from an electron gun into a ring-shaped vacuum tube. The electron beam is deflected by electromagnets or the like to run on a circular orbit through the vacuum tube. The electron beam is further deflected by different, small electromagnets to deviate from the circular orbit and impinge on a ring-shaped target, thereby generating an X-ray toward the center of the vacuum tube. By controlling the small electromagnets, the X-ray generating position is caused to scan at high speed along a circumferential wall of the ring-shaped target.

Abstract: In a computer-assisted tomography (CAT) apparatus, in which a fan-shaped X-ray distribution is rotated about the patients body, it is possible to use a ring of stationary detectors disposed to receive the radiation after passage through the body. In this arrangement the ring of detectors is of smaller radius than the locus of motion of the radiation source. It would appear that this would cause the detectors to obscure the body from the radiation. An arrangement disclosed moves out of the radiation beam those detectors which would present an obstruction so that only those required to collect radiation lie in the beam.